The present invention relates to an image-reproducing method, an apparatus and a photoreceptor thereof and more particularly to a multi-color-image-reproducing method that reproduces multi-color images by the use of an electrophotographic method, a photoreceptor thereof and a multi-color-image-reproducing apparatus therefor.
Many methods for obtaining multi-color images by the use of an electrophotographic method and apparatus to be used for the methods have hitherto been proposed and they are generally classified roughly as follows. In one method thereof, latent-image-formings and developings with color toners are repeated in accordance with the number of color separation wherein a photoreceptor is used and colors are superposed on a photoreceptor or colors are superposed on a transferring member through the transfer onto the transferring member, each time of developing. In the other method, an apparatus having a plurality of photoreceptors according to the number of color separation is used and a light-image of each color is projected on each photoreceptor concurrently with other light-images of other colors and a latent image thus formed on each photoreceptor is developed with color toner and then transferred successively on transferring members, thus multi-color images are obtained after superposing of colors.
In the first method mentioned above, however, a plurality of latent-image-formings and developing processes should be repeated, therefore the image-recording is time-consuming and speedup thereof is very difficult, which is a disadvantage. In the second method mentioned above, on the other hand, a plurality of photoreceptors are used in parallel which is advantageous on the point of speedup but an apparatus tends to be complicated, bulky and expensive because of a plurality of photoreceptors, optical systems and developing units required and thus it is not practical. Further, aforesaid two methods have a serious disadvantage that positioning of images for repetion of image-forming and of transferring in plural times is difficult, thus it is impossible to prevent completely the color-slip on the image.
In Japanese Patent Publication Open to Public Inspection No. 74341/1977 (hereinafter referred to as Japanese Patent O.P.I. Publication), on the other hand, there is disclosed a method wherein a photoreceptor having a filter for colors in mosaic pattern formed on photoconductive layer thereof as an insulating layer is used for reproducing multi-color images but it offers no satisfactory image quality and thereby it has not been put on practical use.